(a) Technical Field
The present disclosure relates to a thin film transistor array panel and a manufacturing method thereof.
(b) Description of the Related Art
In general, flat panel displays, such as liquid crystal displays (LCDs), organic light emitting diode (OLED) displays, and the like, include a plurality of pairs of field generating electrodes and an electro-optical active layer interposed therebetween. LCDs include a liquid crystal layer as the electro-optical active layer, whereas the OLED displays include an organic emission layer as the electro-optical active layer.
One of the pair of the field generating electrodes is typically connected to a switching element to receive an electrical signal, and the electro-optical active layer converts the electrical signal into an optical signal for displaying an image.
Flat panel displays use thin film transistors (TFTs), which are three-terminal elements as the switching elements, gate lines for transmitting scan signals that control the TFTs, and data lines for transmitting signals through the TFTs to pixel electrodes formed on the display.
As the area of a display device increases, the number of signal lines may be increased, and accordingly resistance thereof may also be increased. The increase of resistance may in turn cause a signal delay or a voltage drop, and therefore the signal lines may need to be made of a material having low resistivity, such as for example copper (Cu).
However, when the signal line is made of copper, silane (SiH4) gas may react with the surface of a copper (Cu) line during a process of forming an insulating layer on the copper line, and accordingly copper-silicide (Cu-silicide) is formed, thereby causing the copper layer to be contaminated. At a high temperature, the copper-silicide (Cu-silicide) becomes unstable and thus repeats decomposition and composition, and accordingly the thickness of the copper-silicide (Cu-silicide) increases because silicon (Si) decomposed from the copper-silicide (Cu-silicide) is continuously diffused, thereby increasing the resistance of the copper line.
Therefore, when copper is used as the signal line, a capping layer made of a refractory metal such as, for example, molybdenum or an alloy thereof is formed to cover the copper line so as to prevent the copper line from reacting with silicon (Si).
However, when the capping layer is further formed on the upper portion of the copper line, while unique characteristics of low resistivity wiring can be maintained, manufacturing time may be increased for forming a multi-layer.